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Polycythemia Vera in Dogs

Polycythemia vera is a blood disorder that involves the thickening of the blood due to an overproduction of red blood cells by the bone marrow. It is primarily seen in older dogs.

Symptoms and Types

The following symptoms gradually appear but run a chronic course:

• Weakness
• Depression
• Lack of appetite (anorexia)
• Redness of skin (erythema)
• Increased thirst and urination (polydipsia and polyuria)

Causes

Although the viscosity of the blood is due to an increased production of red blood cells by the bone marrow, the cause of this overproduction is currently unknown.

Diagnosis

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to your veterinarian. He or she will then perform a complete physical examination, as well a biochemistry profile, urinalysis, and complete blood count (CBC). Blood testing will typically reveal an increase in red blood cell mass, and in about 50 percent of dogs, an increased number of white blood cells (leukocytosis).

To assess the function of the kidneys and cardiopulmonary systems, your veterinarian will conduct X-rays and abdominal ultrasounds. Echocardiography, meanwhile, is used to evaluate the cardiac functions. He or she will also take a sample of bone marrow and send it to a veterinary pathologist for further examination.

Treatment

Initially, the veterinarian will draw a fair amount of blood and replace it with intravenous fluids to decrease the blood's viscosity. However, this is only for quick relief. Long-term therapy, for both animals and humans, involve using an antineoplastic drug called hydroxyurea, which suppresses the overproduction of red blood cells in the bone marrow.

Living and Management

During treatment, your veterinarian will need to see the dog for regular follow-up exams, especially when it is taking hydroxurea, as it may sometimes cause bone marrow suppression. In addition, follow the veterinary oncologist's dosage recommendation when using on chemotherapy medications, such as hydroxurea, because these drugs are highly toxic.